When Fruit Turns Harmful: Late Diagnosis of Hereditary Fructose Intolerance in a Pediatric Patient-A Case Report and Literature Review.

INTRODUCTION: Hereditary fructose intolerance is a rare but potentially severe and fatal disorder if it is not recognized promptly. It is caused by biallelic mutations in the ALDOB gene, which encodes the Aldolase B enzyme. Deficiency leads to intracellular accumulation of fructose-1-phosphate, causing secondary inhibition of gluconeogenesis and glucogenolysis and, consequently, hypoglycemia along with hepatic and renal dysfunction. The clinical presentation is variable and often nonspecific, making diagnosis challenging.

CASE REPORT: A 12-year-old boy, born small for gestational age, with a history of hypotonia, laryngomalacia, and persistent hepatomegaly. During his first year of life, he developed an episode of acute hepatitis that required admission to a high-dependency unit due to acute liver failure. Over the following years, he experienced recurrent episodes of vomiting, pallor, diaphoresis, and malaise following the ingestion of sweet foods. During follow-up, he developed syncope secondary to severe hypoglycemia during a fructose tolerance test. Genetic testing revealed a homozygous pathogenic variant in the ALDOB gene, confirming the diagnosis of HFI. A strict diet excluding fructose, sucrose, and sorbitol was initiated, with close multidisciplinary follow-up.

CONCLUSION: HFI represents a diagnostic challenge in pediatrics due to its clinical heterogeneity and its ability to mimic multiple hepatic and metabolic diseases. This case highlights the importance of considering HFI in patients with unexplained gastrointestinal and hepatic symptoms, even beyond infancy. Increased awareness and early diagnosis are critical to prevent misdiagnosis, avoid metabolic decompensation, and ensure excellent long-term outcomes.